IEC Develops Standard to Measure Power Quality of Wind Turbines - IEC 61400-21

September 11, 2008 // Published as a news service by IHS

Developed by IEC Technical Committee 88 on Wind Turbines, IEC 61400-21 sets out the tests that can be used to compare both wind turbines of different types or makes and different electricity grid requirements.

The latter are complex as they typically consider the capability of a wind farm rather than that of a single wind turbine, said the IEC.

About 20 years ago, the common wind turbine was rated at about 50 kilowatts. Today, multi-milliwatt wind turbines are concentrated on big wind farms.

Modern wind farms may control the reactive power or voltage just like any other power plant and may also control active power or frequency as long as wind conditions permit.

Therefore, connecting modern wind power plants to the grid presents similar challenges to those of connecting any other power plant, said the IEC.

Different wind turbine types have different power quality characteristics. IEC 61400-21 provides a uniform methodology to ensure consistency and accuracy in the presentation, testing and assessment of power quality characteristics of grid-connected wind turbines.

The power quality characteristics described in the IEC standard include:

• Wind turbine specifications.
• Voltage quality (emissions of flicker and harmonics).
• Voltage drop response.
• Power control (control of active and reactive power).
• Grid protection.
• Reconnection time.

IEC 61400-21 will be used by wind turbine test stations, research institutes, electric utilities and grid operators, as well as manufacturers of wind turbines and sub-suppliers of electric and control equipment for wind turbines.

Source: International Electrotechnical Commission (IEC).